From: Harry Butterworth <harry@hebutterworth.freeserve.co.uk>
To: Mark Williamson <maw48@cl.cam.ac.uk>
Cc: xen-devel@lists.sourceforge.net, McGroarty <mcgroarty@gmail.com>
Subject: Re: Why are I/O rings bidirectional?
Date: Mon, 07 Feb 2005 23:52:57 +0000 [thread overview]
Message-ID: <1107820377.7818.30.camel@localhost> (raw)
In-Reply-To: <200502072300.09635.maw48@cl.cam.ac.uk>
I think the intended question was "why have both requests and responses
in the same ring rather than have two rings, one for requests and one
for responses?"
On Mon, 2005-02-07 at 23:00 +0000, Mark Williamson wrote:
> > Hello. I am reading Xen and the Art of Virtualization. I am curious as
> > to why the async I/O ring buffers contain both requests and responses
> > in the same ring.
>
> Requests contain details of the IO to be done. Responses notify the domain
> when the IO is complete and whether it was successful or not.
>
> Requests can complete out of order, so it's necessary to have response
> messages following back to the domain to tell it when each request is done.
> If the requests were always dealt with in order it would not be necessary to
> have responses flowing back, so the ring could be unidirectional.
>
> The Safe Hardware Access paper has more details about the IO rings work.
>
> HTH,
> Mark
>
>
> -------------------------------------------------------
> SF email is sponsored by - The IT Product Guide
> Read honest & candid reviews on hundreds of IT Products from real users.
> Discover which products truly live up to the hype. Start reading now.
> http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel
--
Harry Butterworth <harry@hebutterworth.freeserve.co.uk>
-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now.
http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click
next prev parent reply other threads:[~2005-02-07 23:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-07 22:59 Why are I/O rings bidirectional? McGroarty
2005-02-07 23:00 ` Mark Williamson
2005-02-07 23:52 ` Harry Butterworth [this message]
2005-02-08 1:52 ` Mark A. Williamson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1107820377.7818.30.camel@localhost \
--to=harry@hebutterworth.freeserve.co.uk \
--cc=maw48@cl.cam.ac.uk \
--cc=mcgroarty@gmail.com \
--cc=xen-devel@lists.sourceforge.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.